An imaging system includes a developing chamber, a first conveyance path, a second conveyance path, a first air passage and a second air passage. A developing roller located in the developing chamber carries a developer to a developing region where the developing roller is closest to an image carrier. A first stirring-conveying portion is located in the first conveyance path adjacent the developing roller to supply the developer to the developing roller. A second stirring-conveying portion is located in the second conveyance path adjacent the first conveyance path to circulate the developer between the second conveyance path and the first conveyance path. The first air passage has an inlet coupled to the developing chamber and an outlet coupled to the second conveyance path, and the second air passage has an inlet coupled to the second conveyance path and an outlet coupled to the developing chamber.

A pressurization device for a toner cartridge includes an inner cover, an airbag and a sliding member. The inner cover is arranged at a toner feeding port of the toner cartridge; the airbag is made of elastic material; the airbag includes a fixed end that is fixed to the inner cover and a free end that extends outward from the fixed end; the fixed end is provided with an airbag opening interconnected to an interior of the toner cartridge; a remaining portion of the airbag is arranged as closed except for the airbag opening; a first end of the sliding member is connected to the free end of the airbag and moves toward the fixed end of the airbag back and forth, so that the airbag ejects gas into the toner cartridge by means of being compressed.

A cartridge includes a shutter that opens and closes when the cartridge is attached and detached to a developing unit or image forming apparatus. The cartridge includes a casing having a chamber with a first opening at one end portion allowing toner to flow out of the casing. The cartridge includes a cover that covers the first opening, movable with the casing and having a second opening allowing toner to flow out of the cover. The shutter is located at the one end portion and has a protrusion further from the one end portion than the cover. The developing unit supports the protrusion when the cartridge is mounted thereon, and the casing pivots with the cover relative to the developing unit between a first position where the shutter closes the second opening and a second position where a third opening of the shutter overlaps the second opening.

An example device to develop an electrostatic latent includes first and second passages coupled to each other through first and second openings. A first stir-and-transport member located in the first passage includes a first helical blade to stir and transport a developer along the first passage in a first direction and to supply the developer to a developing roller. A second stir-and-transport member located in the second passage includes a second helical blade to stir and transport the developer along the second passage in a second direction. A developer discharge pipe is coupled to the developer container to communicate with a downstream side of the first passage. The first stir-and-transport member includes a first reverse helical blade having a pitch between approximately 0.5 times and 1.5 times the pitch of the first helical blade and located downstream of the first helical blade and disposed downstream of the second opening.

Toner cartridge includes a housing, an agitator, an auger, a first protrusion, and a second protrusion. The housing includes a first toner accommodating portion having and a second toner accommodating portion. The auger is rotatable about a second axis extending in a first direction and is configured to convey toner from a first toner accommodating portion to the second toner accommodating portion. The first protrusion is positioned at a first side of the second toner accommodating portion. The first protrusion extends in the first direction. The second protrusion is positioned at a second side of the second toner accommodating portion and extends in the first direction.

An image forming apparatus includes an image bearer, a developing device, a fixing device, and circuitry. The developing device contains a developer and develops a latent image on the image bearer with the developer. The developing device includes a stirrer to stir the developer. The fixing device fixes a toner image onto a sheet. The circuitry performs start-up operations after receiving a print start command and before starting a printing operation. The start-up operations includes starting a warm-up operation of the fixing device and starting, during the warm-up operation, a stirring operation in which the stirrer stirs the developer.

A cartridge includes a shutter that opens and closes when the cartridge is attached and detached to a developing unit or image forming apparatus. The cartridge includes a casing having a chamber with a first opening at one end portion allowing toner to flow out of the casing. The cartridge includes a cover that covers the first opening, movable with the casing and having a second opening allowing toner to flow out of the cover. The shutter is located at the one end portion and has a protrusion further from the one end portion than the cover. The developing unit supports the protrusion when the cartridge is mounted thereon, and the casing pivots with the cover relative to the developing unit between a first position where the shutter closes the second opening and a second position where a third opening of the shutter overlaps the second opening.

A developer container includes a conveyance member having at least a first sheet member and a second sheet member and configured to convey the developer, a deformation portion provided to contact the first sheet member and configured to elastically deform the first sheet member, and a release portion configured to release elastic deformation of the first sheet member to cause the developer on the first sheet member to fly toward an opening, wherein a containing chamber includes a recessed portion as viewed in a lengthwise direction of the containing chamber and wherein the second sheet member is in contact with a wall inside the recessed portion when the developer on the first sheet member is positioned at the release portion.

A toner case includes a case main body, a cover, and an agitating member. The case main body is configured to contain a toner and to rotate. The cover is configured to cover an opening part arranged at the case main body and to maintain a rotation stop state when the case main body rotates, the cover having a communication space which communicates with an inside space of the case main body via the opening part. The agitating member is configured to rotate integrally with the case main body and to agitate the toner in the communication space.

A toner cartridge includes a casing, a toner conveyance unit, a cover, and a first protrusion. The casing includes a first toner-accommodating section having a first internal space for accommodating toner. The first toner-accommodating section has a first opening. The toner conveyance unit is rotatable and configured to convey toner from the first internal space to the first opening. The cover covers the first opening and has a second opening for allowing toner to be discharged therethrough. The cover has a circumferential surface at which a plurality of gear teeth is provided. The gear teeth are configured to move a developing shutter provided at a developing unit for opening or closing an opening of the developing unit. The first protrusion is configured to release the developing shutter from a locking member of the developing unit for locking the developing shutter.